refactor: feat: 322. Coin Change

coin-change/gwbaik9717.js

@@ -1,33 +1,23 @@
 // n: amount m: length of coins
 // Time complexity: O(n * m) + O(mlogm)
-// Space complexity: O(n * m)
+// Space complexity: O(n)
 
 /**
  * @param {number[]} coins
  * @param {number} amount
  * @return {number}
  */
 var coinChange = function (coins, amount) {
-  const dp = Array.from({ length: coins.length + 1 }, () =>
-    Array.from({ length: amount + 1 }, () => Infinity)
-  );
-  coins.sort((a, b) => a - b);
-
-  for (let i = 0; i < coins.length + 1; i++) {
-    dp[i][0] = 0;
-  }
+  const dp = Array.from({ length: amount + 1 }, () => Infinity);
+  dp[0] = 0;
 
-  for (let i = 1; i <= amount; i++) {
-    for (let j = 1; j <= coins.length; j++) {
-      const coin = coins[j - 1];
-
-      if (i >= coin) {
-        dp[j][i] = Math.min(dp[j][i], 1 + dp[j][i - coin]);
-      }
+  coins.sort((a, b) => a - b);
 
-      dp[j][i] = Math.min(dp[j][i], dp[j - 1][i]);
+  for (const coin of coins) {
+    for (let i = coin; i <= amount; i++) {
+      dp[i] = Math.min(dp[i], dp[i - coin] + 1);
     }
   }
 
-  return dp.at(-1).at(-1) === Infinity ? -1 : dp.at(-1).at(-1);
+  return dp.at(-1) === Infinity ? -1 : dp.at(-1);
 };